[tor-bugs] #28669 [Core Tor/Tor]: Bug: ../src/feature/hs/hs_client.c:280: retry_all_socks_conn_waiting_for_desc

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#28669: Bug: ../src/feature/hs/hs_client.c:280:
retry_all_socks_conn_waiting_for_desc
--------------------------+------------------------------------
 Reporter:  traumschule   |          Owner:  (none)
     Type:  defect        |         Status:  needs_review
 Priority:  Medium        |      Milestone:  Tor: 0.4.0.x-final
Component:  Core Tor/Tor  |        Version:
 Severity:  Normal        |     Resolution:
 Keywords:  tor-hs        |  Actual Points:
Parent ID:                |         Points:
 Reviewer:  asn           |        Sponsor:
--------------------------+------------------------------------

Comment (by asn):

 Given the latest information from traumschule, I have more doubts that the
 comment:3 theory is what's causing the issue here.

 Here is another theory from combining the two log files:

 0) Everything was going great with Tor. It was connecting to a few HSes
 (both v2 and v3s) just fine until 14:04:28.000. And then the clock skew
 happened: `Dec 29 00:10:43.000 [notice] Your system clock just jumped
 36372 seconds forward; assuming established circuits no longer work.`.

 1) After the clock skew, Tor no longer has a live consensus, but it still
 wants to connect to the HSv3s it has the descriptors for.

 2) However, `hs_cache_lookup_as_client()` **cannot see** the cached
 descriptors because it calls `cached_client_descriptor_has_expired` which
 claims that the **descriptor is expired if there is no live consensus**!
 `[info] can_client_refetch_desc(): Can't fetch descriptor for service
 $onion_service. Stalling connection`

 2) The SOCKS connection is now stalled with `AP_CONN_STATE_RENDDESC_WAIT`
 because of (1).

 4) Then after a bit we get a live consensus and
 `retry_all_socks_conn_waiting_for_desc()` gets called, this brings up the
 SOCKS connection from (2) which is still blocked at
 `AP_CONN_STATE_RENDDESC_WAIT`. However, now the descriptor is no longer
 expired because we have a live consensus, and hence there is a valid HS
 desc in the cache and hence the bug triggers.

 ----

 The same issue which is ''that a descriptor cannot be seen when the
 consensus is not live'', is probably also the issue of the original
 poster, so perhaps we can simplify David's patch by not introducing
 `mark_conn_as_waiting_for_circuit()` and calling it when this branch
 triggers. But we still want to remove the Bug() from there.

 Or is there something more **elegant** to do here?

 Removing from needs_revision to figure out next steps.

--
Ticket URL: <https://trac.torproject.org/projects/tor/ticket/28669#comment:8>
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